Heretofore, the discharge doors of a hopper car having generally been opened and closed manually, each door being provided with its own manually actuated latch means by which it may be locked in its closed position. In recent years, hopper cars have been developed which are of greatly increased size and capacity, with larger and heavier hopper doors. Prior art workers have devised for such cars various types of automatic door actuating means by which the large hopper doors may be mechanically opened and closed. At the same time, various types of latch means have been developed to lock the door actuating means in its door-closing position, thereby maintaining the hopper doors in their closed positions.
Prior art door actuator latch means have frequently been characterized by complex structure and have been difficult and expensive to manufacture and assemble. Furthermore, many of the prior art latch means were of such nature that under certain dynamic conditions of the hopper car (including humping, train shocks, train action and slack run-in and run-out), the latch means could unintentionally assume an unlatched condition due to impact inertia, with the possible risk of unwanted discharge of the car load.
Exemplary latch means for automatic door actuating means are taught in U.S. Pat. Nos. 3,710,729 and 3,772,996. U.S. Pat. No. 4,132,177 teaches latch means for automatic door actuating means, which latch means also includes restraint means to prevent the latch from unintentionally assuming an unlatched condition due to impact inertia.
Under some circumstances a complex latch mechanism is not necessary and it is desirable simply to provide the hopper car with restraint means to prevent shifting of the automatic door actuating means to its door-open position due to impact inertia. The present invention is directed to a restraint assembly for a hopper car door actuator of the type comprising a door-actuating beam shiftable longitudinally by a fluid cylinder between door-opening and door-closing positions. Such automatic door actuating means are taught, for example, in U.S. Pat. Nos. 3,187,684 and 3,596,609. The restraint assembly of the present invention is simple in construction and easy to install on the hopper car. The restraint assembly prevents inadvertent hopper door opening when impact inertia tends to extend the piston rod of the fluid cylinder which, in the absence of the restraint assembly of the present invention, could result in the shifting of the door-actuating beam to its door-open position.